Automatic cycling attachment for pressure breathing therapy units



Jan. 6, 1959 v R. BENNETT 2,867,210

AUTOMATIC CYCLING ATTACHMENT FOR PRESSURE BREATHING THERAPY UNITS Filed May 1, 1957 2 Sheets-Sheet 1 INVENTOR. l fw'a/r Ray 54/7/7279 Jan. 6, 1959 v. R. BENNETT 2, 7,

AUTQMATIC CYCLING ATTACHMENT FOR PRESSURE BREATHING THERAPY UNITS 2 Sheets-Sheet 2 Filed May 1, 1957 AUTOMATIC CYCLING ATTACHMENT FOR PRES- SURE BREATHING THERAPY UNITS Vivian Ray Bennett, Yucca Valley, Calif., assignor to Bennett Respiration Products, Inc., a corporation of California Application May 1, 1957, Serial No. 656,377

8 Claims. (Cl. 128-29) especially adapted for use with that type of respirator equipment commonly known in the trade as intermittent positive pressure breathing (I.P.P.B.) units for automatically activating and controlling the operation of the latter.

The invention is primarily concerned with the provision of apparatus having the advantageous attribute that, when employed with the more modern types of I.P.P.B. or respirator units having automatic patient respiration responsive cycling means, the structure of this invention permits the unit to operate in its normal fashion as long as the patient is maintaining his own breathing cycle at a satisfactory rate while assisting him in doing so, but automatically takes over and supplied automatic cycling if the patients respiratory eiforts cease or slow to an unsatisfactory rate.

An important object of this invention is, therefore, to provide apparatus for automatically controlling and operating the cycling valve of an I.P.P.B. or other respirator system during periods when the patient himself is incapable of maintaining proper cycling of respiratory efiorts on his own.

Another important object of this invention is to provide such apparatus which is adapted to respond to, stay in phase with and assist any respiratory efforts on the part 01 the patient as long as such efforts, even though feeble, continue at a respiration rate as rapid as some predetermined minimum, and which is further adapted to automatically take over and automatically operate at a predetermined cycling rate whenever the patients own respiratory efforts cease or slow to a rate less than said predetermined minimum.

Another important object of this invention is to provide such apparatus including means which permit the patient to momentarily over-ride the automatic cycling of the apparatus when his own respiratory effort is to expire or exhale at the same instant that the theretofore existing cycling of the apparatus would otherwise have been artificially inducing inspiration or inhalation, and which further provides for the automatic rephasing or time indexing of the automatic cycling of the apparatus in such manner that subsequent cycling proceeds from the override expiration at the same automatic rate as before but in phase originating from and determined by such override expiration.

Another important object of this invention is to provide such apparatus including shiftable connecting means for quickly and positively coupling or decoupling an actuating member of the apparatus with the cycling valve control element of an associated I.P.P.B. or similar respirator unit of various types, so that a physician can instantaneously shift the operation of the system between fully automatic and manual cycling, if desired.

Another important object of this invention isto provide nited States ,atent 2,867,210 Fatented Jan. 6, 1959 such apparatus wherein certain cooperatively functioning parts are so proportioned and weighted as to give a predetermined, preferred ratio of approximately 3 to 2 between the expiration and the inspiration portions of each cycle of the automatic cycling operation of the apparatus regardless of the characteristics frequency of such cycling. Basically, the illustrated embodiment of the invention utilizes a stationary base, an elongated arm pivotally mounted on the base intermediate its ends for swinging movement about a horizontal axis, a vertical bellows closed at its top and thereat pivotally connected with the arm adjacent one end of the latter and open at its bottom and thereat secured to the base, a tube coupled with the bottom of the bellows and adapted for being oppositely coupled with the conduit leadingfrom the cycling valve to the mask of an I.P.P.B. or other respirator unit, a preferably adjustable restriction or control valve in series with-the tube, and means on the opposite end of the arm adapted for being operably coupled with the shiftable control element of the cycling valve of the unit. Passage presenting means having a check valve therein and oppositely communicating with the atmosphere and the tube between the control valve and the bellows are also preferably provided, with the check valve being disposed for entry of air from the atmosphere to the bellows only.

Further details of the structure, construction and operation of the apparatus contemplated by the invention, as well as still further important objects thereof, will be made clear or become apparent from the description that follows:

In the accompanying drawings:

Fig. 1 is a fragmentary, front elevational view of the control unit and certain associated parts of an I.P.P.B. type respirator system having an illustrative embodiment of automatic cycling attachment as contemplated by this invention connected therewith, certain parts being broken away and shown in section for clarity;

Fig. 2 is an enlarged cross sectional view of the automatic cycling attachment per se looking from front to rear thereof, as from the line II-II of Fig. 3;

Fig. 3 is an enlarged, essentially bottom plan view of the attachment per se looking from the line III-III of Fig. 2 and showing the attachment connecting tube in cross-section;

Fig. 4 is an enlarged, fragmentary, cross sectional view of the attachment per se, taken on line IVIV of Fig. 2;

Fig. 5 is an enlarged, fragmentary, top plan view of the attachment per se and associated portions of the control unit of the I.P.P.B. respirator system, showing the trip yoke in solidlines in its operative or automatic cycling position and in dotted lines in its inoperativeor manual control position;

Fig. 6 is a further enlarged, fragmentary, cross sectional view of the trip yoke and a portion of the actuating arm of the attachment on which it is carried, taken on line VI-VI of Fig. 5;

Fig. 7 is an enlarged, fragmentary cross sectional View of the check valve portion of the attachment, taken on line VII-VII of Fig. 2;

Fig. 8 is an enlarged, exploded, fragmentary view of the rotation limiting means associated with the shaft of the control valve of the attachment; and

Fig. 9 is a further enlarged, cross sectional view of the valve aperture portion of the control valve shaft of the attachment, taken on line IXIX of Fig. 8.

Referring now to the structure illustrated in the drawings, the numeral it generally designates a pressure breathing therapy unit of an I. P. P. B. type respirator system. The unit 10 chosen for illustration is a Bennett Model TV-ZP and includes a housing 12 adapted to be mounted directly upon a tank of oxygen or the like (not shown) forming a part'of the overall system. 'Unit 10 conventionally may include a pressure regulating valve control knob 14, a mask pressure gauge 16, a control pressure gauge 18, for indicating the pressure of gas supplied through the regulating valve controlled by knob 14to'the cycling valve 20, and a flow sensitive cycling valve 20. r

jAflexi ble, main hose 22 serves 'as a' conduit between the unit '10 and a patient mask (not shown), it being understood that such mask is coupled by hose 22 and unit It) with the mentioned gas supply tank through the cycling valve 20 of unit and the pressure regulating valve associated with knob 14. The numeral 24 designates an auxiliary hose coupled-with the unit 10, entering the mainhose 22 as at a seal 26 and operative in connection with the control of a remote pressure actuated valve (not shownywhich may be associated with the mask portion of the system.

The purpose and manner of functioning of the auxiliary hose 24, as well asthe form that. cycling valve may take, will be more clear upon reference to the disclosure of U. S. Letters Patent No. 2,483,722 issuedto me on October 4, 1949. Since the details of neither of such matters is material to the present invention, the reference to my said previously disclosed and patented valve will virtually suffice. It should be noted,'however, that the valve 20, althoughactually a three-way, selector valve assembly whose operation is controlled by the effect of the patients own respiratory efforts on decade of flow of gas to the mask, operates, insofar as the connection thereof betweenthe gas supply source and the mask of the systemv is concerned, essentially as an on-off type valve for cycling the periods during which gas pressure is applied to the mask with alternate periods during which no gas is applied to the mask. During the alternate periods between application of'gas to the mask, the

cycling valve 20 closes the gas supply line and vents the 1 hose 22 to the atmosphere for exhalation. The valve 20 includes a cover plate 28 having an arcuate slot 39 therein through which a valve controlling element inthe nature of an elongated pin 32 extends (see plate 51, slot 83 and pin 82 of the disclosure of the above-mentioned patent); the pin 32 is shiftable along the extent of slot 30,

the cycling valve being opened when the pin 32 approaches the upper extremity of slot 30 and closed as the pin 32 approaches the lower extremity of slot 30; and the particular valve 20 is so constructed that, when the pin 32 is raised past a certain intermediate level in the slot 30, it will continue to rise to the upper extremity of slot 36 without further external force being applied thereto andwill remain at such upper extremity of slot 30 until forced downwardly.

3 It is reiterated that the valve 20 preferably is of the type referred to, which automatically relieves the hose 22 of pressure during expiration of the patient and applie pressure from the tanks to hose 22 during inspiration of the patient.

Attention is now directed 'to the attachment contemplated by this invention which is generally designated by the numeral 40, it being understood thatthe structure of which attachment 40 is comprised could be built into the unit 10 as an original part thereof, if desired.

1 Attachment 40 includes a vertical base plate 42 attached to housing 12 of unit 10 as by screws 44. An elongated actuator arm 46 is pivotally mounted on plate 42 for swinging movement about a horizontal axis by a stub pin 48 provided with a lock ring 50. Pivotally suspended from a horizontal pivot pin 52 on the arm 46 adjacent one end of the latter is a rod 54 having an in verted, pan-like,bellows-supporting cup 56 on itslower extremity. An annular weight piece 58 is disposed on rod 54 and rests upon cup 56. An open-bottomed, closed-topped, vertical bellows 60 of rubber or similar flexible material has its top wall 62 adhesively secured to the underside of cup 56 and its open, bottom extremity elastically fitted over an upwardly facing nipple 64 of a block 66 mounted on plate'42 as by screws 68.

Block 66 is provided with an elongated, vertical bore 70 therethrough communicating at its upper extremity with the interior of collapsible bellows through the nipple 64. A tubular connector 72 is provided at the lower end of bore 7 0 and serves to connect the latter with one end of an elongated, flexible tube 74. The other end of tube 74 is provided with means such as a tubular, needle connector 76 for effecting a coupling of the tube 74 with the main hose 22. The tube 74 is preferably provided with a small, replaceable pellet of cotton or the like 78 therein for filtering out any foreign matter.

Block 66 is also provided with a horizontal bore 80 therethrough intersecting the bore at a right angle. Rotatably but relatively snugly received Within the bore is a control valve shaft 82 extending through the bore 80 and provided with an adjustment knob 84 secured on one end thereof by a setscrew 86. Intermediate its ends and in coincidence with the bore 70, the shaft 82 is provided With a segment shaped groove 88 and a sub stantially semi-crescent shaped groove 90 communicat-- ing with groove 88 at one extremity of the latter. Groove 88 and 90 cooperate with the adjacent wallsof bore 70 to present a restriction in the latter, which forms a control valve that is accurately adjustable in even small increments as the shaft 82 is rotated by means of knob 84.

It will benoted that the positioning of the shaft 82 controls the rate of flow of gas between tube 74 and bellows'60 in both directions and, therefore, controls both the expansion and deflation intervals of each cycle for the bellows 60. It is also significant that the arm 46 is so proportioned, fulcrumed and weighted and the weight 58 is preferably so chosen that the ratio of inspiration interval to expiration interval of each automatic cycle is approximately 3 to 2.

It has been found desirable to provide means for limiting the rotation of shaft 82 in one direction to aposi tion whereat themaximum restriction which can be-presented in bore 70 does not constitute a complete closure of the latter and is, intact, such that the rate of-flow permitted through bore 70 with the knob in its minimum" flow position will sustain cycling of the attachment 40 (and hence valve 26) at a rate which constitutesthephysiologically determined, minimum, safe respiration rate, namely, about 8 to 10 cycles per minute. This is accomplished by means including a disc 92 having a forwardly facing stop projection 94 thereon adjustabl-y mounted on plate 42 by means of-a threaded we 96 extending rearwardly from disc'92 through plate 42 and secured after adjustment by a lock nut 98. A cross pin 100 passes through shaft 82 adjacent the rear end of the latter, which pin 100 is adapted to engage the stop projection 94 on disc 92. Block 66 may be conveniently hollowed out as at 102 to accommodate pin 100 and disc 92, and an annular spring 104- and annular washer 106 on shaft 82 and oppositely bearing against block 66 and pin 100 may be providedto bias shaft 82 in a direction for positive engagement of pin 100 with projection 94.

Means for effecting an operable connection between the armt46 and the control element of a valve .20 may be of various kinds depending upon the nature of the valve 20 and its operating element. With the preferred typev of valve 20 described for illustration and having a more or less vertically shiftable pin 32 for an operating element, however, the preferred coupling structure includes a yoke 108 pivotally connected to arm '46 .at

the end of the latter nearest pivot 48 and remote from bellows 60 by a generally vertical pivot pin 110. The

has a rider cup 112 slidably mounted in a concavity 114 of yoke 108 and biased by a coil spring 116 toward engagement with either the mentioned plane end or the front side of arm 46, depending upon whether the yoke is releasably locked in its operative or its inoperative position.

Yoke 108 has a pair of legs 118 and120 vertically spaced by a distance greater than the diameter of the pin 32 and adapted to extend respectively above and below the pin 32 for alternate engagement with the latter when the yoke is in its operative position indicated by solid lines in Fig. 5; When yoke 108 is shifted to the dotted line position of Fig. 5, attachment 40 continues to operate but is not coupled with pin 32 of valve 20 for controlling the latter, whichis then presumably being manually cycled by the physician through manipulation of pin 32. It will be apparent that a switch over from automatic to manual control, or vice versa, can be made almost instantaneously by simply shifting the yoke 108 between its alternate positions.

It'should be noted that the spacing of the legs 118 and 120 as described is to be preferred, since leg 120 immediately raises pin 32 upon closing of bellows 60, while there is a desired, lost motion interval before leg 118 forces pin 32 downwardly to close valve 20 during the opening of bellows 60 attending the inspiration portion of each cycle.

In order to provide for the possibility of patient override of the automatic cycling control of Valve 20 by attachment 40, as for example when the patient coughs just as the pin 32 reaches its upper position for applying gas under pressure to the mask for inspiration by the patient, an in-flow only check valve is provided by a concavity 122 in block 66, a tubular insert 124 fitted in concavity 122 and having an upwardly facing seat 126 thereon, and a disc-like valve member 128 within concavity 122 and normally biased by gravity into closing relationship upon the seat 126 of insert 124. A limiting pin 130 for valve member 128 extends downwardly into concavity I22, and insert 124 may be internally threadedas at 132 to facilitate attachment of a removing tool. A horizontal bore 134 in block 66 plugged as at 136 oppositely communicates with concavity 122 above valve member 128 and with bore 70 between bore 80 and nipple 64. Insert 124 may be secured in block 66 by a screw 138.

It will be understood that the check valve assembly 128 I 7 just described, provides a by-pass to the atmosphere for the bellows 60 to permit quick filling of the latter-when the patient coughs or otherwise expires at a time when the apparatus is at the .inspiration portion of a cycle with the cycling valve 20 open and the pin 32 at the upper extreme of its path of travel. The change of gas flow caused by the out-of-phase cough or other expiration is sensed by the cycling valve 20and operates to reverse the condition of the latter to shut off the supply of gas under pressure and vent the mask and hose 22 to the atmosphere. In so reversing its condition, the valve 20 shifts the pin 32 from the upper extremity to the lower extremity of its path of travel. Were it not for the provision of the mentioned check valve assembly 128, it will be apparent that the bellows 60 could fill only through the grooves 83-90 of control valve 82 and that the bellows 60 would thereby tend to slow or resist the sudden shifting of pin 32 that occurs responsive to the patients cough or other out-of-phase exhalation.

A cover 140 is provided for bellows 60 and block 66,

which is cut away as at 142 to clear arm 46. A lower limit stop pin 144 is preferably provided on plate 42 for limiting swinging movement of the arm 46 in a direction attending deflation of bellows 60, in order to prevent excessive collapsing of the latter.

Operation in operation, and assuming first that the patient is not respirating through his own efforts, upon turning the pressure control valve 14 of unit 10 and such tank or tank 'line valves (not shown) as may be provided to their open positions, oxygen or other gas will flow from tanks through pressure valve 14, open cycling valve 20 and hose 22 to the mask, it being noted that the cycling valve 20 will be open since the pin 32 will be held at the uppermost extremity of its path of travel by the weight of arm 46, piece 58, etc. during stand-by periods when the bellows 60 remain deflated. This supplies the pressure required at the mask for inducing the first inspiration by the patient. Such pressure applied to hose 22 is also transmitted through the tube 14 and the grooves 88-90 of the control valve 82 to the bellows 60 by way of bore 70 of block 66. The bellows 60 thereupon inflate and expand at a rate dependent upon the adjustment of the control valve ,knob 84, such expansion of bellows 60 being effective to raise the end of actuating arm 46 to which the bellows 60 is attached by pivot pin 52 and the rod and cup assembly 5456. As actuating arm 46 thus swings about its fulcrum pivot 48, leg 118 of yoke 108, if the same is in its operative position, is lowered through an interval of lost motion until the pin 32 of cycling valve 20 is engaged and ultimately depressed toward the lower extremity of slot 30, thereby closing the valve 20 as the bellows 60 reaches full expansion. i 0' Upon the closing of cycling valve 20 by virtue of the full depression of pin 32 byleg 118 of yoke 108, the pressure applied to hose 22 will be relieved, and the bellows 60 will contract under the influence of weight 58 and the weight of the rod and cup assembly 5'456, as well as the normal beam unbalance of weight of the arm 46 toward that end thereof. The rate of contraction and collapse of the bellows 60 is controlled by the set-- bore 70, the control valve grooves 8890 and the tube 74 to the hose 22 from which the gas pressure has been relieved by the closing of-the cycling valve20. After the bellows 60 has contracted a predetermined amount swinging'the actuating arm in a corresponding direction, the lower leg 1200f yoke 108 will have raised the control element on pin 32 of the cycling valve 20 to a level where the valve 20 is slightly opened, whereupon the valve 20 by its own nature and action will then fully open itself, thereby raising the pin 32 to the upper extremity of slot 30. It will be apparent that the relieving of pressure from the hose 22 which permits the contraction of the bellows 60 also permits and induces expiration by the patient.

Upon the reopening of the cycling valve 20 at the termination of the expiration portion of each cycle, the hose 22 is again pressurized with gas from the supply tank to induce the next inspiration, which will be accompanied by another expansion ofbelows 60 and closing of the cycling valve 20 in the manner above described.

Next, assume that the attending physician desires to temporarily control the respirator system by manual operation of the cycling valve 20. He has merely to swing the yoke 108 from its operative position to its inoperative position, as shown in dotted lines at 108' in Fig. 5, whereupon the attachment 40 will be effectively decoupled from the pin 32 and the latter cleared for manipulation by the physician. When it is desired to return to automatic control of the cycling valve 20 by the attachment 40, the physician has merely to swing the yoke 108 back to its operative position with the legs 118 and 120 thereof respectively above and below the control element pin 32 of th'e'cycling valve 20.

Assume finally, that the control valve knob 84 of the attachment 40 has been set for automatically cycling the operation of the cycling valve 20 and, therefore, the respiration of a patient, at some predetermined rate, and

So long as the cycling rate of the patients own respiratory efforts exceeds that rate at which the attachment 40 has been adjusted, the operation of the system will be substantially the same'as if the attachment 49 were not being employed, since, under such circumstances the cycling valve 20 will itself respond to the changes in gas flow caused by the respiratory efforts of the patient to open and close itself, thereby alternately .pressurizing and relieving the pressure from the hose 22 as the patient inspires and expires respectively. Such application and relief of p'ressureto the hose-22 is, of course, transmitted through the tube 74 to the attachment 40 which tends to cycle at the same rate as the patients own respiratory efi'orts.

It is significant that the operation of the attachment 40, andparticularly the bellows 60 thereof with its interconnected actuating a'rm 46, is kept in phase with the patients own breathing efforts-by a rephasing of the operation of the attachment 40 each time the patient expires, since each time the patient expires out of phase with the cycling of attachment 40 the resultant change of gas flow in the hose 22' is sensed by the valve 20 which changes its condition, thereby shifting the pin 32 to the lower extremity of its path of travel, the check valve 128being operable to permit quick filling of the bellows 60fso that the latter will not resist the natural action of the pin 32 as long as the valve 20 is cycling at a rate equal to or greater than that of attachment 40. The attachment '40 is thus maintained in continuously readjusted phase relationship to the patients own respiratory efforts, so that, if suchefforts cease or slow unduly, the attachment 40 will take over with automatic cycling of the cycling'valve 20 in properly phased relationship to the patients most recently independent respiratory effort.

If the patients respiratory efforts do cease or sloW. unduly, the attachment 40 immediately assumes control of the pin 32 of cycling valve 20, with the cycling opera tion being essentially as first above-described for the case where the respiratory system is being used on a patient who had no independent respiratory action. Note, however, that, by virtue of the rephasingof attachment 40; during the expiration portion of each phase'of the operation of valve 20 responsive to the patients own breathing efforts, when the system shifts to automatic control by attachment 40, the firstcycle of automatic patient responsive operation. t

It will now be apparent'that the structure contemplated and provided by this invention is ideally adapted for accomplishing all of the above-mentioned and other" objects thereof. It will be equally clear, however, that a number of minor modifications or changes could'be made from the exact details of construction disclosed'for purposes of illustration without departing from thetrue spirit orf intention of'the invention. Accordingly, it is to be understoodthat the invention shall be deemed limited only by the scope of the claims that follow.

operation will follow in exact phase with the last cycle of V e Having thus I described the invention, what is claimed as new and desired to be secured by Letters Patent is ,1. Combined pneumatic and mechanical oscillatory, control apparatus for use with a respirator system ineluding a source of gas under pressure, an administering mask and a three-way, cycling valve adapted for operation either by means of its own responsiveness to a patients breathing efforts or under manual control and having an inlet port adapted for coupling with the source, a yent port adapted for communication with the atmos phere, an outlet port'adapted for coupling with the mask, a lshiftable, flow sensitive valve member adapted for placing the outlet portin communication alternately with the inlet port and the vent port and an exposed, manually shiftable, operating elcrnentsccured to the rnember for manually'opera ting the latter, said control apparatus bewithout manual assistance whenever the breathing efforts vi i'g adapted for'automatically operating the cycling valve shiftable mechanism ad'apted for mechanical couplingwith the element rorrnovin the'latter to shift the mem- 1 ber when the mechanism is shifted; means mechanically coupled with and yieldably urging the mechanism toward one end of its path of travel for shifting'the element and thereby the member to a disposition placing the outlet port of the cycling valve in communication with the inlet port of the latter; and pneumatically actuable, shiftable structure mechanically coupled with the mechanism for shifting the latter, when the structure is actuated, against the urging'of the means toward the opposite end of the path of travel of the mechanism for shifting the element and thereby: the member to a disposition placing the outlet port of the .cycling'valve in communication with the vent portof the latter, said structure being adapted for pneumatic-coupling with the outlet port of the cycling valve for automatically actuating the structure whenever the member is in the first-mentioned disposition thereof placing the outlet port of the cyclingvalve in communication with the inlet port of the latter and for automatically deactuating the structure whenever the member is in the second-mentioned disposition thereof placing the outlet port of the cycling valve in communication with the vent port of the latter.

2. Apparatus as set forth in claim 1, wherein is provided means for controlling the rate of gas flow in at least one direction between the outlet port of the cycling valve'and the structure, whereby a finite period of time is normally required for a complete cycle of actuation and freactuation of the structure.

3. In automatic cycling apparatus for use with a respirator unit having a cycling valve provided with an'exposed, shiftable, operating element and a hose coupled with the cycling valve and adapted for coupling with a gas administering mask, the combination of: a base; an elongated arm pivotally mounted on the base intermediate itsends; coupling means at one end of the arm adapted for operative engagement with the elementfor shifting the latter as the arm is moved; a bellows'having an open extremity and a closed extremity; structure mounting the bellows adjacentits open extremity upon the base; connecting means at the opposite end of the arm operably coupled with the closed extremity of the ellows for movement of the arm by the bellows as the latter'is inflated or deflated; and a fluid carryin'gconduit coupled with the open extremity of the bellows and adapted to be oppositely coupled with thehose; and a flow control valve interposed in the conduit;

4. Apparatus as set forth in claim 3, wherein is provided a check valve having an inlet side and an outlet side, the inlet side being in communication with the atmosphere, the outlet side being in communication with the conduit at a Zone of .the latter between the flow control valve and the bellows.

5. In automatic cycling apparatus for, use with a respirator 'unit having a cycling valve provided with an exposed, shiftable, operating element and a hose coupled with the cycling valve and adapted for coupling with a gas administering mask, the combination of: abase; an elongated arm pivotallyrnounted on the base intermediate its ends; coupling means at one end of thearm adapted for operative engagement with the element for shifting the latter as the arm is moved, said coupling mean's com: prising a bifurcated yokelmounted on the .arm and having apair of spaced, opposed legs adapted to receive a portion of the element therebetween; a. bellows having an open extremity and .a closed extremity; structure varm operably coupled with the closed extremity of the bellows 'for movement of the arm by the bellows as the latter-is inflated and deflated; and a fluid carrying con- I duit coupled with the open extremity of the bellows and adapted to be oppositely coupled with the hose.

6. In automatic cycling apparatus for use with a respirator unit having a cycling valve provided with an exposed, shiftable, operating element and a hose coupled with the cycling valve and adapted for coupling with a gas administering mask, the combination of: a base; an elongated arm pivotally mounted on the base intermediate its ends, said arm being mounted to pivot upon a horizontal axis; coupling means at one end of the arm adapted for operative engagement with the element for shifting the latter as the arm is moved; a bellows having an open extremity and a closed extremity, said bellows being disposed on the base for expansion and contraction of the bellows in a vertical direction; structure mounting the bellows adjacent its open extremity upon the base; connecting means at the opposite end of the arm operably coupled with the closed extremity of the bellows for movement of the arm by the bellows as the latter is inflated and deflated; a fluid carrying conduit coupled with the open extremity of the bellows and adapted to be oppositely coupled with the hose; and weight means carried by the arm on that side of its pivotal axis opposite said one end thereof, whereby the relative duration of the filling and emptying phases of the operation of the bellows may be controlled to a predetermined ratio.

7. Apparatus as set forth in claim 5, wherein the legs of the yoke are spaced apart a distance greater than the corresponding dimension of said portion of the element, whereby only one of the legs of the yoke may engage the element at a given time.

8. Apparatus as set forth in claim 5, wherein the yoke is pivotally mounted on the arm adjacent said one end of the latter, said one end of the arm is substantially planar and substantially perpendicular to a side face of the arm, and the yoke is provided with a spring biased rider member adapted to alternately engage the one end and said side face of the arm when the yoke is shifted between a pair of extreme positions for respectively receiving and clearing the element. 7

References Cited in the file of this patent UNITED STATES PATENTS 1,044,031 Drager Nov. 12, 1912 2,288,436 Cahan June 30, 1942 2,711,170 Bernstein June 21, 1955 

